Study On The Effect Of Chemical Modification Of Steel Surface On Polymer Coating Properties

Polymer coating has gradually demonstrated its excellent potential due to its protective properties to metal materials.Nano-filler,multi-composition,surface decoration and modification can bring more improvements to the performance of polymer composite coatings.The research can be applied to a complex dynamic environment and it could effectively improve wear-resistant anti-friction composite coatings for the useful life of friction equipment and components in the marine environment.It is one of the key technologies of marine resources development and marine strategy implementation in China.However,when the traditional polymers are used as coatings,it can meet the problem of weak tribological properties of steel matrix and weak tribology.These problems greatly affect the widespread application of polymer coatings on the surface of metal parts.Therefore,in this study,a composite polymer coating with strong bonding performance to the substrate,excellent anti-corrosion performance,and good overall performance was prepared for the friction components on the surface of the sliding guide rail in a corrosive environment.The thesis used Materials Studio to establish the interface model of steel substrate and epoxy resin coating under different conditions.Then,analyzing that when there has different kinds of iron oxides generated on the surface of steel,the VDW?van der Waals force?force between the steel substrate and the epoxy resin coating will be increased,while the electrostatic force will be decreased.At the same time,analyzing the phenomenon that when the hydroxylation,phenolization,and silanization of are performed on the steel surface,the VDW force increased while the electrostatic force decreased.In addition,when optimizing the structure of the organic conversion film and the bonding interface of epoxy resin coating,the epoxy resin coating and the organic conversion film form a tight cross-linking structure and generate a certain amount of hydrogen bonds.These phenomena are conducive to the enhancement of the binding force.Finally,analyzing that when an appropriate amount of graphene is added to the epoxy resin coating,the VDW force of the interface between the epoxy resin composite coating and the steel substrate can be improved.In order to increase the bonding strength between the epoxy resin coating and the steel substrate,the thesis studies on the epoxy resin preparation and the filler addition.By using SEM test,EDS test,FT-IR test,electrochemical test and binding force test,the effects of different temperatures,tannic acid content,tartaric acid content and silane coupling agent KH560 content on the performance of the composite organic conversion film are investigated.According to the test,the main elements of the conversion film are C,O,Mo,Si,etc.and contain a certain amount of benzene ring carbonyl and other organic components.When the conversion liquid temperature is 35°C,the tannic acid content is 4g/L,the tartaric acid content is 1 g/L.Besides,when the silane coupling agent KH560 content is 20g/L,the binding force between the polymer coating and the steel matrix can be 2.4 times as high as that unconverted film.To some extent,the prepared conversion film also improves the corrosion resistance ability of steel matrix.At last,In order to strengthen the tribological properties of epoxy resin on steel matrix,the thesis studies on the preparation process of epoxy resin and the addition of fillers.By using SEM test,EDS test,friction and wear test and electrochemical workstation test,the effects of high temperature curing time,type of curing agent,type of diluent,nano-Al₂O₃content,and graphene oxide content on the coating of epoxy resin are investigated.According to the result of the test,it can be seen that when epoxy coating using polyamide resin as the curing agent and anhydrous ethanol as diluent,then curing three days with 70 degrees,there has a good bonding force between the epoxy resin coating and steel matrix.In addition,when the content of added nano-Al₂O₃ is 2%,the friction coefficient between the epoxy resin composite coating and the steel ball can be reduced from about 0.7 that the filler is not added to about 0.5 after the modification.At the same time,the wear resistance of the modified coating can also be improved.Therefore,by adding nano Al₂O₃ in the epoxy resin composite coating,the tribological properties can be effectively improved and protect the steel matrix better.Moreover,by using steel conversion film and polymer modification,the bonding force between the steel matrix and the polymer coating can be improved and the polymer coatings has a better anti-corrosion effect.This extends the use life of the parts and has a strong application value.